Material melting device of metal injection molding machine

ABSTRACT

A material melting device of metal injection molding machine comprises a main feeding cylinder; a plurality of preheat feed cylinders parallel arranged at a lateral side of a main feeding cylinder of a metal injection molding machine; a plurality of material inlets formed at a side of each preheat feed cylinder. The material inlets are communicated to the main feeding cylinder through the guide tubes. Thereby, an inner side of the preheat feed cylinder is pre-heated so as to get preheat grains by adjusting the preheat screw rods in the preheat feed cylinder. Moreover, the preheat feed cylinders can be replaced by feeding funnels and the guide tubes are replaced by heating pipes.

FIELD OF THE INVENTION

[0001] The present invention relates to metal injection molding machines, and particularly to material melting device of metal injection molding machine which will cause the injecting material has a solid structure so that the surface of the product is smooth.

BACKGROUND OF THE INVENTION

[0002] Injecting machines are mainly used with shaping molds for forming products. Materials are heated, extruded and then feed to a mold. Conventionally plastic material is used due to low melting point, small grain sizes and preferred uniformity. Moreover, in the process of storage and injection, the material has no bubble therein.

[0003] Currently, many products, for example, computer casings, use metals as material (for example, aluminum) for replacing plastic material. However, metals are heavy and dense than plastics. Moreover, the grains of the metal after melting are not so uniform as plastic grains. Thereby, conventionally, a feeding screw rod with screw threads at the middle section is used to feed material, but this will induce bubbles to be accumulated in the metal material. As a result, the surface of the product is not uniform or gaps are formed in the wall of the product.

[0004] Referring to FIG. 1, a prior art thixomolding method disclosed in U.S. Pat. No. 5,040,589 is illustrated. In this conventional way, metal grains are machined as a great deal of chips. Thereby, in transferring by the feeding screw rod, it is heated as a mixing structure containing solid grains and liquids, and for a long period, the material becomes a viscosity material. The defect of this prior art is that the chip must be retained in a viscosity condition, neither liquid nor solid can exist. This is very difficult, especially to control the temperature in operation.

[0005] Referring to FIG. 2, a first class rheomolding method disclosed in U.S. Pat. No. 6,405,784 is shown. In this prior art way, the device used is improved from the conventional used one. Grain-like material is melt as liquid in a transversal material feeding cylinder. Then the material is fed to a following inclined cylinder by using a piston. Then the melt material is pushed into a mold by the piston.

[0006] Referring to FIG. 3, a first class rheomolding method disclosed in U.S. Pat. No. 5,501,266 is shown. In this prior art way, the device used is improved from the conventional used one. The block-like metal is melt and thus is supplied to a screw rod so that melt material can be injected into a mold.

[0007] In above two Rheomolding methods, the melting metal must be retained in a viscous state from a liquid state for being placed in the mold to form a desired shape. Thereby, the temperature must be reduced from a high temperature. However, this is difficult in a long and continuous operation. To control the metal in a steady state is very difficult. Moreover, these two methods generate more bubbles than the prior art method so that the smoothness of the product is not preferred.

SUMMARY OF THE INVENTION

[0008] Accordingly, the primary object of the present invention is to provide a material melting device of metal injection molding machine. The device comprises a main feeding cylinder; a plurality of preheat feed cylinders being parallel arranged at a lateral side of a main feeding cylinder of a metal injection molding machine. A plurality of material inlets are formed at a side of each preheat feed cylinder. The material inlets are communicated to the main feeding cylinder through the guide tubes. Thereby, an inner side of the preheat feed cylinder is pre-heated so as to get preheat grains by adjusting the preheat screw rod in the preheat feed cylinder.

[0009] Another object of the present invention is to provide a material melting device of metal injection molding machine, The device comprises a main feeding cylinder; a plurality of preheat feed funnels arranged at a lateral side of a main feeding cylinder of a metal injection molding machine. Each funnel is connected to the main feeding cylinder through a respective heating pipe; thereby, an inner side of the funnel is pre-heated so as to get preheat grains by adjusting the preheat screw rods in the preheat feed cylinders;

[0010] The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 shows an operational structure of a prior art thixomolding method.

[0012]FIG. 2 shows an operational structure of a prior art first class rhomolding method.

[0013]FIG. 3 is an operational structure of a prior art second class rohmolding method.

[0014]FIG. 4 is a schematic view about the operation structure of the coating molding of the present invention.

[0015]FIG. 4A is a partial enlarged schematic view of the coating molding operation of the present invention.

[0016]FIG. 4B is a schematic view showing the preheat process of the coating molding of the present invention.

[0017]FIG. 4C is a schematic view showing that the preheat grains are mixed with melt material in the coating molding method of the present invention.

[0018]FIG. 5 shows a structural schematic view of the present invention.

[0019]FIG. 6 is a schematic view showing another embodiment of the present invention.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Referring to FIGS. 4 and 4A, in the present invention, a lateral side of a main feeding cylinder 2 of a metal injection molding machine is arranged with a plurality of preheat feed cylinders 3 which are parallel arranged. A side of each preheat feed cylinder 3 is formed with a plurality of material inlets 31A, 31B and 31C. The material inlets 31A, 31B and 31C are communicated to the main feeding cylinder 2 through the guide tubes 4A, 4B and 4C. Thereby, the inner side of the preheat feed cylinder 3 can be pre-heated so as to get preheat grains 5A, 5B and 5C by adjusting the preheat screw rods 32 in the preheat feed cylinders 3.

[0021] The material 5 drops into the main feeding cylinder 2 from the material inlets 31A, 31B and 31C. The material 5 dropped from the material inlet 31A forms the preheat grains 5A which are hard, the material 5 dropped from the material inlet 31B forms the preheat grains 5B, the material 5 dropped from the material inlet 31C forms the preheat grains 5C. The preheat grain 5A are harder than preheat grains 5B and the preheat grains 5B are harder than preheat grains 5C.

[0022] Moreover, the material 5 is directly supplied to the main feeding cylinder 2, and thus it is formed as a liquid material 5D which are mixed with the preheat grains 5A, 5B and 5C. Thereby, the injecting material has a solid structure so that the surface of the product is smooth.

[0023] In the present invention, the number of the material inlets are changeable according to the property of the material and other conditions. Moreover, the number of the preheat feed cylinders 3 are also changeable.

[0024] Referring to FIG. 6, the second embodiment of the present invention is illustrated. In this the present invention, the material inlets may be replaced by feeding funnels 33 and the guide tube is replaced by heating pipes 6. This arrangement can generate the same effect as the previous embodiment.

[0025] The present invention is thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. 

What is claimed is:
 1. A material melting device of metal injection molding machine comprising a main feeding cylinder; a plurality of preheat feed cylinders being parallel arranged at a lateral side of the main feeding cylinder of a metal injection molding machine; a plurality of material inlets being formed at a side of each preheat feed cylinder; the material inlets being communicated to the main feeding cylinder through the guide tubes; thereby, an inner side of the preheat feed cylinder being pre-heated to get preheat grains by adjusting the preheat screw rods in the preheat feed cylinders; wherein material drops into the main feeding cylinder from the material inlets to be as preheat grains; preheat grains have different hardness due to dropping time of the material dropping into the main feeding cylinder; moreover, another material is directly supplied to the main feeding cylinder, and thus it is formed as a liquid material which are mixed with the preheat grains.
 2. The material melting device of metal injection molding machine comprising a main feeding cylinder; a plurality of preheat feed funnels arranged at a lateral side of the main feeding cylinder of a metal injection molding machine; each funnel being connected to the main feeding cylinder through a respective heating pipe; thereby, an inner side of the funnel being pre-heated to get preheat grains by adjusting the preheat screw rods in the preheat feed cylinders; wherein material drops into the main feeding cylinder from the heating pipes to be as preheat grains; preheat grains have different hardness due to dropping time of the material dropping into the main feeding cylinder; moreover, another material is directly supplied to the main feeding cylinder, and thus it is formed as a liquid material which are mixed with the preheat grains. 